Optical gesture sensor having a light modifying structure

ABSTRACT

A gesture sensing device includes a single light source and a multiple segmented single photo sensor, or an array of photo sensors, collectively referred to herein as segmented photo sensors. A light modifying structure relays reflected light from the light source onto different segments of the segmented photo sensors. The light modifying structure can be an optical lens structure or a mechanical structure. The different segments of the photo sensor sense reflected light and output corresponding sensed voltage signals. A control circuit receives and processes the sensed voltage signals to determine target motion relative to the segmented photo sensor.

RELATED APPLICATIONS

This application claims priority of U.S. provisional application Ser.No. 61/483,034, filed May 5, 2011, and entitled “Gesture Sensing Methodand Apparatus”, by these same inventors. This application incorporatesU.S. provisional application Ser. No. 61/483,034 in its entirety byreference.

FIELD OF THE INVENTION

This invention relates to displays for electronic devices. Morespecifically, this invention relates to a device that senses anddetermines physical gestures.

BACKGROUND OF THE INVENTION

A gesture sensor is a human interface device that enables the detectionof physical movement without the user actually touching the devicewithin which the gesture sensor resides. The detected movements can besubsequently used as input commands for the device. In someapplications, the device is programmed to recognize distinct non-contacthand motions, such as left to right, right to left, up to down, down toup, in to out, and out to in hand motions. Gesture sensors have foundpopular use in handheld devices, such as tablet computing devices andsmartphones, and other portable devices, such as laptops. Gesturesensors are also being implemented in video game consoles that detectthe motion of a video game player.

Most conventional gesture sensor implementations use three or moreillumination sources, such as light emitting diodes (LEDs), and a lightsensor, such as a photo detector. The illumination sources are turned onand off, or flashed, in succession in order for the sensor to obtainspatial information from reflection of the flashed light. FIG. 1illustrates a simplified block diagram of a conventional gesture sensor.A photo sensor 4 is positioned proximate LED 1, LED 2, and LED 3. Acontrol circuit 5 is programmed to successively turn on and off the LEDs1-3 and analyze the resulting measurements sensed by the photo sensor 4.FIG. 2 illustrates an exemplary method for detecting a moving targetusing the gesture sensor of FIG. 1. The motion is detected by observingthe relative delay between sensed signals from the same-axis LEDs. Forexample, to detect left to right or right to left motion, the signalssensed by the LEDs 1 and 2 are compared, as shown in FIG. 2. LED 1 isflashed at a different time than LED 2. The LEDs 1 and 2 are positionedin known locations and are turned on and off in a known sequence. Whenthe light from the LEDs strikes a target moving above the LEDs, light isreflected off the moving target back to the photo sensor 4. The sensedreflected light is converted to a voltage signal which is sent to thecontrol circuit 5. The control circuit 5 includes an algorithm that usesthe LED positions, the LED firing sequences, and the received senseddata to determine relative movement of the target.

FIG. 2 shows the sensed voltage signals for the case of left to rightmotion. A sensed voltage signal is a voltage versus time curve. Thecurve labeled “Signal from LED 1” shows the sensed voltage resultingfrom repeated flashes of the LED. The low portion of the curve indicatesthe target is not passing over, or near, the LED 1. In other words, thetarget is not within the “field of view” of the photo sensor 4 wherebylight emitted from the LED 1 can be reflected off the target and ontothe photo sensor 4. If the target is not within the field of view of thephoto sensor 4 as related to the LED 1, the photo sensor 4 does notsense any reflections of light emitted from LED 1. The high portion ofthe curve indicates the target is passing over, or near, the LED 1. Thecurve labeled “Signal from LED 2” shows the sensed voltage resultingfrom repeated flashes of the LED 2. While LED 1 is on, LED 2 is off, andvice versa. While the target is positioned over, or near, LED 1, thesensed voltage related to flashing of LED 1 is high, but the sensedvoltage related to flashing of the LED 2 is low. While the target ispositioned in the middle, between the two LEDs 1 and 2, the photo sensor4 detects reflected light from flashing of both LED 1 and LED 2. Whilethe target is positioned over, or near, LED2, the sensed voltage relatedto flashing of LED 2 is high, but the sensed voltage related to flashingof the LED 1 is low. When the target is not positioned over either LED 1or LED 2 or between LED 1 and LED 2, the photo sensor 4 does not sensereflected light associated with either and the corresponding sensedvoltage levels are low.

For left to right motion, the sensed voltage level for “signal from LED1” goes high before the sensed voltage level for “signal from LED 2”, asshown in FIG. 2. In other words, the voltage versus time curve of“signal from LED 2” is delayed relative to the voltage versus time curveof “signal from LED 1” when the target is moving from left to right.

FIG. 2 also shows the sensed voltage signals for the case of right toleft motion. For right to left motion, the sensed voltage level for“signal from LED 2” goes high before the sensed voltage level for“signal from LED 1”, as shown in the two voltage versus time curves onthe left hand side of FIG. 2. In other words, the voltage versus timecurve of “signal from LED 1” is delayed relative to the voltage versustime curve of “signal from LED 2” when the target is moving from rightto left.

Up and down motion, where up and down are considered to be motion in they-axis, is similarly determined using LEDs 2 and 3 and the correspondingvoltage versus time data. The control circuit 5 receives the sensedvoltage from the photo sensor 4 and determines relative target motion inthe y-axis in a similar manner as that described above in relation tothe x-axis.

A disadvantage of the multiple illumination source configuration is themultiple number of illumination source components that must beintegrated within the device. With ever decreasing device size,additional components are undesirable.

SUMMARY OF THE INVENTION

A gesture sensing device includes a single light source and a multiplesegmented single photo sensor, or an array of photo sensors,collectively referred to herein as segmented photo sensors. A lightmodifying structure relays reflected light from the light source ontodifferent segments of the segmented photo sensors. The light modifyingstructure can be an optical lens structure or a mechanical structure.The different segments of the photo sensor sense reflected light andoutput corresponding sensed voltage signals. A control circuit receivesand processes the sensed voltage signals to determine target motionrelative to the segmented photo sensor.

In an aspect, a device to determine a physical gesture is disclosed. Thedevice includes a single illumination source; a plurality of lightsensors; a light modifying structure to relay reflected light to theplurality of light sensors, wherein the reflected light is light fromthe single illumination source reflected off a target object; and aprocessing circuit coupled to the plurality of light sensors to analyzetime dependent signals received from the plurality of light sensors andto determine target object directional movement proximate to the device.

The illumination source can be a light emitting diode. Each light sensorcan be a photodiode. The plurality of light sensors can be an array ofindividual light sensors or a single light sensor partitioned intomultiple segments. In some embodiments, the light modifying structure isan optical lens structure. In other embodiments, the light modifyingstructure is a mechanical structure configured to selectively block aportion of the light depending on a position of the target objectrelative to the plurality of light sensors. In the case of a mechanicalstructure, each light sensor can be formed as a plurality of cellstructures, each cell structure having two photodiodes, further whereinthe mechanical structure can include a plurality of wall structures, onewall structure per cell wherein the wall structure is positioned betweenthe two photo diodes. In some embodiments, a top layer of each wallstructure has an outer perimeter that does not overlap either of the twophotodiodes. In other embodiments, a top layer of each wall structurehas an outer perimeter that partially covers each of the twophotodiodes. Each wall structure can include a plurality of metal layersand a plurality of dielectric layers, a dielectric layer separating eachmetal layer, wherein each dielectric layer includes a plurality of metalthrough vias that couple to metal layers on either side of thedielectric layer. In some embodiments, the plurality of wall structuresare fabricated using semiconductor manufacturing processes.

In some embodiments, each wall structure is perpendicular to a topsurface of the one or more photodiodes. In other embodiments, each lightsensor includes a plurality of cell structures, each cell structureincluding one or more photodiodes, further wherein the mechanicalstructure includes a plurality of wall structures, one wall structureper cell wherein the wall structure is at a non-perpendicular angle to atop surface of the one or more photodiodes. In this non-perpendicularconfiguration, each wall structure can include a plurality of metallayers and a plurality of through vias configured in a stair-stepstructure.

In some embodiments, each light sensor includes a plurality of cellstructures, each cell structure including two photodiodes, furtherwherein the mechanical structure includes a plurality of slotted metallayers, one slotted metal layer per cell wherein the slotted metal layeris positioned above the two photo diodes and an open slot of the slottedmetal layer is aligned with a center point between the two photodiodes.Each cell can also include a dielectric layer positioned between thephotodiodes and the slotted metal layer, wherein the dielectric layer isoptically transparent. In other embodiments, the plurality of lightsensors are formed on an integrated circuit chip, and each light sensoris a photodiode, further wherein the mechanical structure includes achip package coupled to the integrated circuit chip, the chip packageincluding a wall structure positioned between each of the photodiodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a simplified block diagram of a conventional gesturesensor.

FIG. 2 illustrates an exemplary method for detecting a moving targetusing the gesture sensor of FIG. 1.

FIG. 3 illustrates a conceptual diagram of the gesture sensing deviceaccording to an embodiment.

FIGS. 4 and 5 illustrate exemplary composite signals generated fromsignals output from the segmented photo sensor in response to a targetmoving in various directions.

FIG. 6 illustrates a cross section view of a sundial configurationaccording to an embodiment.

FIG. 7 illustrates a top down view of the cell of FIG. 6.

FIG. 8 illustrates the cell of FIG. 7 rotated by 90 degrees.

FIG. 9 illustrates a top down view of a plurality of cells configured toform four Segments.

FIG. 10 illustrates across section view of a sundial configurationaccording to an alternative embodiment.

FIG. 11 illustrates a cross section view of a sundial configurationaccording to yet another alternative embodiment.

FIG. 12 illustrates across section view of a pinhole configurationaccording to an embodiment.

FIG. 13 illustrates a top down plan view of the cell of FIG. 12.

FIG. 14 illustrates a cross section view of a canopy configurationaccording to an embodiment.

FIG. 15 illustrates a top down view of a corner quad configurationaccording to an embodiment.

FIG. 16 illustrates a cross section view of the corner quadconfiguration of FIG. 15.

FIG. 17 illustrates an exemplary implementation of the angled walls usedin the Venetian blinds configuration.

FIG. 18 illustrates adjacent cells in the Venetian blinds configuration.

FIG. 19 illustrates a top down view of a micro quad cell configurationaccording to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present application are directed to a gesture sensingdevice. Those of ordinary skill in the art will realize that thefollowing detailed description of the gesture sensing device isillustrative only and is not intended to be in any way limiting. Otherembodiments of the gesture sensing device will readily suggestthemselves to such skilled persons having the benefit of thisdisclosure.

Reference will now be made in detail to implementations of the gesturesensing device as illustrated in the accompanying drawings. The samereference indicators will be used throughout the drawings and thefollowing detailed description to refer to the same or like parts. Inthe interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions will likelybe made in order to achieve the developer's specific goals, such ascompliance with application and business related constraints, and thatthese specific goals can vary from one implementation to another andfrom one developer to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

Embodiments of a gesture sensing device include a single light sourceand a multiple segmented single photo sensor, or an array of photosensors. By adding a light modifying structure, such as an optical lensstructure or a mechanical structure, the reflected light can be focusedand/or directed onto different segments of the photo sensor. Thedifferent segments of the photo sensor sense reflected light at the sametime, and the relative amplitude from each segment is indicative ofmovement of the target. A control circuit receives and processes thesensed data from the segmented photo sensor to determine target motionrelative to the segmented photo sensor. The one light sensorconfiguration is more compact and less expensive than multiple sourceconfigurations. Another advantage of the gesture sensing device is thata user can convey a device command through gesturing without the need toactivate a touch screen controller, or use of mechanical buttons. Thisprovides significant power and cost savings.

FIG. 3 illustrates a conceptual diagram of the gesture sensing deviceaccording to an embodiment. The gesture sensing device 10 includes asingle illumination source, represented as LED 11, and a segmented photosensor 12. In some embodiments, the segmented photo sensor 12 isconfigured to sense only a specific wavelength or wavelengths of light,such as the wavelengths emitted by the illumination source 11. Such aconfiguration can be implemented through the use of a filter. Thesegmented photo sensor 12 can be either a single sensor functionallypartitioned into multiple segments or an array of individual photosensors. For example, a quad segmented photo sensor is functionallyequivalent to four individual photo sensors arranged in a quad layout.As used herein, reference to a “segment” refers to either a partitionedsegment within a single sensor or to an individual sensor in an array ofsensors. FIG. 3 shows the segmented photo sensor 12 as both on-edge(upper element labeled 12) and a plan view to show the differentsegments (lower element labeled 12).

In the exemplary configuration of FIG. 3, the segmented photo sensor 12includes four segments, segment A, segment B, segment C, and segment D.Although a four segment detector is the simplest implementation, it isunderstood that the number of segments can be increased to increase theresolution of the system. The signal processing electronics becomeincreasingly more complex as the number of segments is increased. Eachof the segments is isolated from each other. The LED 11 is positionedproximate to the segmented photo sensor 12. When a moving target passesproximate to the LED 11 and the segmented photo sensor 12, light outputfrom the LED 11 is reflected off the moving target and to the segmentedphoto sensor 12. The gesture sensing device 10 also includes an opticallens structure 13 to focus light onto the segmented photo sensor 12. Thefocusing lens focuses reflected light from a moving target, such as ahand gesture, in the space above the segmented photo sensor 12. It isunderstood that only reflected light that is within the “field of view”of the optical lens structure 13 is focused onto the segmented photosensor 12. Although shown as a single element 13 in FIG. 3, the opticallens structure 13 represents any number of lens and/or optical elementsfor directing light to the segmented photo sensor 12. An exemplaryimplementation of an optical lens structure and/or light sensor isdescribed in the co-owned and co-pending U.S. Provisional PatentApplication Ser. No. 61/490,568, filed May 26, 2011, and entitled “LightSensor Having Glass Substrate With Lens Formed Therein” and the co-ownedand co-pending U.S. Provisional Patent Application Ser. No. 61/491,805,filed May 31, 2011, and entitled “Light Sensor Having Glass SubstrateWith Lens Formed Therein”, which are both incorporated in theirentireties by Reference. Each segment of the segmented photo sensor 12outputs a segment signal to a control circuit 14, where the segmentsignals are processed.

The LED 11 is continuously or periodically energized to illuminate thetarget. The light reflected from the target induces the segment signalon each of the segmented photo sensors. These segment signals areprocessed and stored in a buffer memory, the buffer memory beingintegrated with or separate from the control circuit 14. The controlcircuit 14 analyzes the stored data and determines if a valid gesturehas been detected. The same data can be also be used so that thesegmented photo sensor 12 operates as a proximity detector. The samephoto sensor structure can be used with a different signal processingcircuit so that the gesture sensing device also functions as an ambientlight sensor.

When the LED 11 is powered on, or flashes, the target is illustrated ifthe target is within a proximate space above the segmented photo sensor12. The moving target is conceptually illustrated in FIG. 3 as a flatreflector. The target reflection is imaged by the optical lens structure13 onto the segmented photo sensor 12. The example of FIG. 3 illustratesa right to left motion of the target. As the edge of the target movesthrough the center of the imaging zone, the focused image of the targetedge moves across the segmented photo sensor 12. The segments A and Crespond first to the moving image, followed by segments B and D. Thecontrol circuit 14 is programmed to detect this sequence of events, andrecognizes a right to left target motion. Similarly, a left to righttarget motion can be recognized by the opposite sequence, and both up todown and down to up target motions can be recognized using theorthogonal set of signals. The in and out target motion can berecognized by sensing the absolute amplitude of the sum of the foursegments A-D, which is also the proximity measurement.

FIGS. 4 and 5 illustrate exemplary composite signals generated fromsignals output from the segmented photo sensor 12 in response to atarget moving in various directions. A composite signal is a compositeof two or more segment signals, each segment signal provides sensedvoltage versus time data. The composite signals and method of analyzingthe composite signals shown in FIGS. 4 and 5 show one exemplary methodof how to analyze the segment signals for determining target motion. Itis understood that alternative methods of analysis can be applied to thesegment signals to determine relative target motion.

Referring to FIG. 4, to determine if a target is moving from right toleft or from left to right, the segment signals from segment A andsegment C are added together to form composite signal A+C, and thesegment signals from segment B and segment D are added together to formcomposite signal B+D. FIG. 4 illustrates exemplary composite signalscorresponding to the determination of right to left or left to rightmotion of the target. The composite signal B+D is subtracted from thecomposite signal A+C to form a differential composite signal(A+C)-(B+D). If right to left motion is present, the differentialcomposite signal (A+C)-(B+D) has a positive peak followed by a negativepeak, as shown in the bottom left curve of FIG. 4. If left to rightmotion is present, the differential composite signal (A+C)-(B+D) has anegative peak followed by a positive peak, as shown in the bottom rightcurve of FIG. 4.

Notice in FIG. 3, that the direction of motion of the target is oppositethat of the affection of motion of the image on the segmented photosensor 12. Image inversion is a result of the optical lens structure 13.In alternative embodiments, described in detail below, the optical lensstructure is replaced by one of a number of mechanical structures. Insome embodiments of these alternative configurations, the image on thesegmented photo sensor 12 moves in the same direction as the target, andthe composite signals (A+C) and (B+D) shown in FIG. 4 are swapped andthe differential composite signal (A+C)-(13+D) is inverted. As shown inFIG. 3, when the target moves from right to left, the image on thesegmented photo sensor 12 moves from left to right. As applied to FIG.4, when the target moves from right to left, then the image initiallyappears on segments A and C as the target is on the right, but the imagedoes not yet appear on segments B and D, and the resulting compositesignal A+C starts to increase, as shown in the top left curve of FIG. 4,but the composite signal B+D remains at zero. As the target moves to theleft, the image starts to appear on segment B+D while still appearing onsegments A+C, and the resulting composite signal B+D starts to increase,as shown in the middle left curve of FIG. 4. Eventually, the image fullyappears on all segments A-D. When the trailing edge of the target imagemoves off of segments A and C, the composite signal A+C returns to zero,and the negative peak of the differential composite signal (A+C)-(B+D)is formed.

Similarly, when the target moves from left to right, then the imageinitially appears on segments B and D as the target is on the left, butthe image does not yet appear on segments A and C, and the resultingcomposite signal B+D starts to increase, as shown in the top right curveof FIG. 4, but the composite signal A+C remains at zero. As the targetmoves to the right, the image starts to appear on segment A+C whilestill appearing on segments B+D, and the resulting composite signal A+Cstarts to increase, as shown in the middle right curve of FIG. 4.Eventually, the image fully appears on all segments A-D. When thetrailing edge of the target image moves off of segments B and D, thecomposite signal B+D returns to zero, and the positive peak of thedifferential composite signal (A+C)-(B+D) is formed.

Up and down movement is similarly determined. To determine if a targetis moving from up to down or from down to up, the segment signals fromsegment A and segment B are added together to form composite signal A+B,and the segment signals from segment C and segment D are added togetherto form composite signal C+D. FIG. 5 illustrates exemplary compositesignals corresponding to the determination of up to down or down to upmotion of the target. The composite signal C+D is subtracted from thecomposite signal A+B to form a differential composite signal(A+B)-(C+D). If down to up motion is present, the differential compositesignal (A+13)-(C+D) has a positive peak followed by a negative peak, asshown in the bottom left curve of FIG. 5. If up to down motion ispresent, the differential composite signal (A+B)-(C+D) has a negativepeak followed by a positive peak, as shown in the bottom right curve ofFIG. 5.

When the target moves from down to up, then the image initially appearson segments A and B, hut the image does not yet appear on segments C andD. The resulting composite signal A+B starts to increase, as shown inthe top left curve of FIG. 5, but the composite signal C+D remains atzero. As the target moves downward, the image starts to appear onsegment C+D while still appearing on segments A+B, and the resultingcomposite signal C+D starts to increase, as shown in the middle leftcurve of FIG. 5. Eventually, the image fully appears on all segmentsA-D. As in the right to left motion, with down to up motion thedifferential composite signal (A+B)-(C+D) exhibits a positive peakfollowed by a negative peak, as shown in the bottom left curve of FIG.5. It can be easily seen that the opposite motion, up to down, forms asimilar differential composite signal (A+B)-(C+D), but with the oppositephase, as shown in the bottom right curve of FIG. 5.

Additional processing is performed to determine motion toward and awayfrom the segmented photo sensor, referred to as in and out motion. Todetermine in and out motion, all four segments A, B, C, D are added toform a composite signal A+B+C+D. If the composite signal A+B+C+Dincreases over a given time period, then it is determined that there ismotion toward the segmented photo sensor, or inward. If the compositesignal A+B+C+D decreases over a given time period, then it is determinedthat there is motion away from the segmented photo sensor, or outward.

In general, the segments are measured and the segment signals areprocessed as appropriate to determine changes in magnitude of thecomposite signals. These changes in magnitude, when compared temporallywith changes in magnitude of other composite signals, determine relativemotion of a target reflecting light back to the segmented photo sensor.

In alternative embodiments, mechanical structures are used in place ofthe optical lens structure. Mechanical structures are used to influencehow the reflected light is directed to the segmented photo sensor. Afirst mechanical structure is referred to as a sundial configuration.The sundial configuration implements a physical “wall” protruding from asensor surface of the segmented photo sensor. The wall effectively castsa “shadow” on various sensor segments as the target moves across thespace above the segmented photo sensor. This shadow is tracked andtarget motion is correspondingly determined.

FIG. 6 illustrates a cross section view of a sundial configurationaccording to an embodiment. The sundial configuration provides amechanical means for directing reflected light onto a photo sensor, inthis case a photodiode. The center structure is the physical sundialwall used to block reflected light. The two N-EPI to P-SUBSTRATEjunctions on either side of the wall form two photodiodes. The wall is aseries of metal layers built up to separate the two photo diodes. In theexemplary configuration of FIG. 6, the wall includes a first metal layerM1, a second metal layer M2, a third metal layer M3, and a top metallayer TM. Each metal layer is separated by a passivation layer, such assilicon dioxide within which through-vias are formed. The metal layers,passivation layers, and through-vias are formed using conventionalsemiconductor processing techniques. The wall is formed on a substratedoped to form the photodiodes, also referred to as a cell. The firstphotodiode, or photodiode cell A, is formed by an N-EPI to P-SUBSTRATEjunction. A metal contact M1 is coupled to the N-EPI region in order tomake contact to the photodiode cell A cathode. The P-SUBSTRATE serves asthe photodiode anode, and it is common for both the photodiode cells Aand B cells. There is an additional photodiode formed by adding a P-WELLlayer on top of the N-EPI layer of photodiode cell A. A contact for theP-well is made at the end of the P-well, not shown in FIG. 6. In someembodiments, the P-well photodiode is used to measure ambient light whenthe gesture function is not used. Such a configuration and functionalityis described in the co-owned U.S. patent application Ser. No.12/889,335, filed on Sep. 23, 2010, and entitled “Double LayerPhotodiodes in Ambient Light Sensors and Proximity Detectors”, which ishereby incorporated in its entirety by reference. The second photodiode,photodiode cell B, is formed in a manner identical to the photodiode Acell. The two photodiode cells A and B are isolated by two P+ diffusionsthat extend through the N-EPI region and contact the P-SUBSTRATE. Anisland of N-EPI is formed between the two P+ isolation diffusions. Thisisland forms an additional diode that collects any stray photocurrentthat might migrate from under photodiode cell A and otherwise becollected by photodiode cell B. The additional diode also collects anystray photocurrent that might migrate from under photodiode B and beotherwise collected by photodiode cell A. Together, the two P+ isolationdiffusions and the N-EPI island in between them form the A/B isolationregion. The three elements of the A/B isolation region are all shortedby the first metal layer M1, which is connected to ground at the topmetal layer TM. Any photocurrent collected in the composite A/Bisolation region is shunted to ground, reducing crosstalk betweenphotodiode cell A and photodiode B.

The structure in FIG. 6 is a cell that includes photodiode cell A,photodiode cell B, the isolation region, and the wall. FIG. 7illustrates a top down view of the cell of FIG. 6. This cell isconfigured to determine left-right motion as the wall is alignedperpendicularly to the direction of motion, left-right, to bedetermined. To determine up-down motion, the cell is rotated 90 degrees,as shown in FIG. 8. In the cell configuration of FIG. 8, the wallstructure is aligned perpendicularly to the up-down motion to bedetermined. A reason for creating cells is that the size of thephotodiode cells is restricted, specifically the width of the photodiodeextending away from the wail structure. This limits the surface areathat can be used to measure the reflected light. FIG. 9 illustrates atop down view of a plurality of cells configured to form four blocksaccording to an embodiment. Each cell is isolated from an adjacent cellby an isolation region 1. In FIG. 9, block 1 is made of an array ofalternating photodiode cells A and B. Block 1 is identical to block 4which also include an array of alternating photodiode cells A and B. Allof the photodiode cells A in both blocks 1 and 4 are shorted together toform an aggregated A node. Aggregating the array of cells increasessignal strength. Likewise, all of the photodiode cells B in both blocks1 and 4 are aggregated together to form a single B node. The sameconnection scheme is used to form a C node and a D node from the arrayof alternating photodiode cells C and D in blocks 2 and 3. Thephotodiode cells in blocks 2 and 3 are rotated 90 degrees relative tothe photodiode cells in blocks 1 and 4. In this manner, there are fourdistinct signals, one from each of nodes A, B, C, and D.

Target motion in the left-right and up-down directions is againdetermined by analyzing differential signals. To determine target motionin the left-right direction, the differential signal A-B is formed. Thedifferential signal A-B is analyzed in a similar manner as thedifferential composite signal (A+C)-(B+D) related to the quad cellconfiguration of FIG. 3. To determine target motion in the up-downdirection, the differential signal C-D is formed. The differentialsignal C-D is analyzed in a similar manner as the differential compositesignal (A+B)-(C+D) related to the quad cell configuration of FIG. 3.

The cell structure shown in FIG. 6 is an exemplary sundial configurationand alternative structures are also contemplated. FIG. 10 illustrates across section view of a sundial configuration according to analternative embodiment. In the alternative configuration of FIG. 10, thewall is alternatively formed, and the underlying substrate isalternatively doped. In this embodiment, the isolation region betweenthe two photodiode cells A and B consists of a single P+ diffusion. Thesmaller isolation region of FIG. 10 compared to that of FIG. 6 allowsfor increased packing density. P-WELL and N-EPI region contacts are madeat the end of the array, not shown in FIG. 10. The P+ region in thesubstrate is connected to ground at the top metal layer TM.

FIG. 11 illustrates a cross section view of a sundial configurationaccording to yet another alternative embodiment. In the alternativeconfiguration of FIG. 11, the wall is alternatively formed, and theunderlying substrate is alternatively doped. The photodiode cells do notinclude a P-WELL in this configuration. The N-EPI region contacts aremade at the end of the array, not shown in FIG. 11. The P+ isolationregion between the photodiode cells A and B is connected to ground atthe top metal layer TM. In this embodiment, the absence of the P-WELLlayer permits the fabrication of narrower photodiode cells A and Bcompared to that of FIG. 6. This structure affords higher cell packingdensity compared to that of FIG. 6.

A second mechanical structure is referred to as a pinstripeconfiguration. FIG. 12 illustrates a cross section view of a pinstripeconfiguration according to an embodiment. The pinstripe configurationprovides a mechanical means for directing reflected light onto a photosensor, in this case a photodiode. The pinstripe configuration isanalogous to a pinhole camera, where the pinhole has been elongated intoa stripe or slot. The two N-EPI sections in the substrate form thecathodes of photodiode cells A and B, with the P-SUBSTRATE forming thecommon anode. A metal layer M3 is formed over the cell, and an open slotis formed in the metal layer. The metal layer is formed over aninterlayer dielectric, such as silicon dioxide, which is opticallytransparent. The metal layer and open slot are formed using conventionalsemiconductor manufacturing processes. In some embodiments, the cellstructure is formed using conventional CMOS, digital semiconductormanufacturing processes. FIG. 13 illustrates a top down plan view of thecell of FIG. 12. As shown in FIG. 13, the open slot is aligned along alength of the cell. The open slot can run the entire length or partiallength of the cell

In operation, reflected light passes through the open slot and impingesthe photodiodes, N-EPI sections. When a target position is on the rightside of the open slot, light reflected from the target passes throughthe open slot and impinges the left side photodiode cell A. As thetarget moves from right to left, more reflected light impinges the leftside photodiode cell A until the target passes a critical angle whereless reflected light impinges the left photodiode cell A and instead,reflected light begins to impinge the right side photodiode cell B. Whenthe target is directly overhead the slot, at a crossover point, thesignals received from the photodiode cells A and B are the same. This isthe position of highest overall signal strength, and is also where thedifference between the two signals, A-B, is zero. As the targetcontinues moving to the left, more reflected light impinges the rightside photodiode cell B, and the difference signal, A-B, changes sign andbecomes negative. After further leftward motion of the target, zeroreflected light impinges the left side photodiode cell A. Similarly tothe sundial configurations, a plurality of cells of the pinholeconfiguration are adjacently positioned to form a block, and the signalsfrom the individual photodiode cells A are aggregated together to formthe common A node. The same type of signal aggregation is used for the Bthrough D signals. The alignment of the open slot determines thedirection of target motion to be determined. For example, the horizontalalignment of the open slot in FIG. 13 is used to determine up-downmotion. A plurality of cells aligned such as the cell in FIG. 13 form asegment configured to measure up-down motion. Vertical alignment of theopen slot is used to determine left-right motion. In an exemplaryconfiguration, the segments having the pinstripe configuration arealigned in a similar manner as those segments having the sundialconfiguration as shown in FIG. 9 where segments A and D are configuredto determine left-right motion and segments B and C are configured todetermine up-down motion. Target motion in the left-right and up-downdirections is determined using the differential signals in the samemanner as the sundial configuration described above.

In alternative configurations, the metal layer and open slot can bereplaced by any type of light obscuring element that enables light toenter through a defined area and block light elsewhere, such as a MEMS(micro-electro-mechanical systems) device or other levered, or partiallyfloating element, where the obscuring element is supported by anoptically transparent material or suspended over air proximate the openslot. A MEMS device is a very small mechanical device driven byelectricity.

An alternate embodiment is the application of the pinstripe concept tothe quad cell design to produce a micro quad cell. FIG. 19 illustrates atop down view of a micro quad cell configuration according to anembodiment. The micro quad cell consists of an array of small quadcells. All of the individual A segments are aggregated together to forma single A signal, and likewise so are the B, C, and D segments. Thearray of quad cells is covered by a metal layer that has square or roundopenings that let light through. The metal layer is formed in a mannersimilar to that described for the pinstripe concept, using asemiconductor process. The dimensions of the quad cells A through D, themetal layer spacing, and the dimension of the opening in the metal layerare consistent with the dimensions typically available in semiconductorprocesses. The openings in the metal layer are positioned so that whenlight is directly overhead the opening, all cells are equally, butpartially illuminated. When the angle of the light changes, the relativeillumination of the four cells becomes imbalanced. The four signals, Athrough D, are processed in a manner identical to that describedpreviously for FIG. 3.

A third mechanical structure is referred to as a canopy configuration.The canopy configuration operates similarly as the pinstripeconfiguration except that instead of reflected light accessing thephotodiodes of a cell through an open slot in the center of the cellstructure, as in the pinhole configuration, the center of the cellstructure is covered by a “canopy” and the peripheral sides of thestructure are open to allow reflected light to access the photodiodes ofthe cell. FIG. 14 illustrates a cross section view of a canopyconfiguration according to an embodiment. The canopy configurationprovides a mechanical means for directing reflected light onto a photosensor, in this case a photodiode. The two N-EPI sections formphotodiode cells A and B. A top metal layer TM forms a canopy over thecenter of the cell structure, thereby covering an inner portion of thephotodiodes but not covering an outer portion. The top metal layer is atop layer of a wall formed as a series of metal layers built thatseparate the two photodiode cells A and B. The wall structure is formedin a similar manner as the wall structures of the sundialconfigurations, except that the top metal layer TM of the canopyconfiguration extends over portions of the two photodiode cells A and B.The portion of the top metal layer TM that extends over the twophotodiodes cells A and B is formed over an interlayer dielectric (notshown), such as silicon dioxide, which is optically transparent.Similarly to the pinstripe configuration and sundial configurations, aplurality of cells of the canopy configuration are adjacently positionedto form a segment, and multiple segments are configured and oriented todetermine left-right and up-down motion. Reflected light is sensed bythe photodiode cells A. and B, and the sensed voltage is collected andprocessed similarly as for the pinstripe configuration and sundialconfiguration described above.

A fourth mechanical structure is referred to as a corner quadconfiguration. The corner quad configuration is similar conceptually tothe sundial configuration in the use of a physical wall positionedbetween photo sensing elements, but instead of implementing the wall atthe silicon level and having a plurality of cells for each segment, asin the sundial configuration, the corner quad configuration isimplemented at the chip package level where a wall is formed between thesegments. FIG. 15 illustrates a top down view of a corner quadconfiguration according to an embodiment. FIG. 16 illustrates acrosssection view of the corner quad configuration of FIG. 15. In theexemplary configuration shown in FIGS. 15 and 16, photo sensor segmentsA-D are formed as four photodiodes on an integrated circuit chip. Thefour photodiodes can be considered as identical to the four photodiodesof FIG. 3, except that instead of using the closely spaced quad geometryof FIG. 3, the photodiodes are instead spaced apart and placed in thefour corners of the substrate. The integrated circuit chip is packagedin a chip package that includes a wall made of optically opaque materialthat blocks light, such as the light reflected from a moving target. Theportion of the chip package above the photodiodes is made of anoptically transparent material. The height of the wall in the cornerquad configuration is high enough so that each segment is a singlesensor element, as opposed to a plurality of cells as in the sundial andcanopy configurations. Determination of the target motion is determinedin a similar manner as the sundial configuration without having toaggregate the individual cell voltages for a given segment. The cornerquad configuration includes a wall that has a chip package level ofmagnitude versus the sundial configuration that includes a wall that hasa transistor level of magnitude.

A fifth mechanical structure is referred to as a Venetian blindsconfiguration. The Venetian blinds configuration is similar to thesundial configuration except that the wall structure in each cell isformed at a non-perpendicular angle to the photodiode cell(s), asopposed to the perpendicular angle as in the sundial configuration. Theangled walls are fabricated by forming metal layers and through-vias ina stair step configuration, as shown in FIG. 17. Additionally, each cellin the Venetian blind configuration includes a single photodiode cellpositioned on one side of the angled wall, as shown in FIG. 18. In theVenetian blind configuration, each of the four segments is facing adifferent 90 degree direction. For example, segment A is configured withthe walls angled to the left, segment B is configured with the wallsangle upward, segment C is configured with the walls angled downward,and segment D is configured with the walls angled to the right. In otherwords, each segment has a different field of view. Using thesealignments, target motion in the left-right and up-down directions isdetermined using the differential signals in the same manner as thesundial configuration described above. It is understood that alternativealignments can be used.

In some embodiments, filters are added on top of the photo sensors tofilter out light having wavelengths that are different than theillumination source.

The exemplary embodiments describe a gesture sensing device having foursymmetrically configured segments, or photo sensors. It is understoodthat the concepts described herein can be extended to more than foursegments configured symmetrically or asymmetrically, as in an N×N, N×M,circular, or other shaped array of photo segments or sensors.

The gesture sensing device has been described in terms of specificembodiments incorporating details to facilitate the understanding of theprinciples of construction and operation of the gesture sensing device.Such references, herein, to specific embodiments and details thereof arenot intended to limit the scope of the claims appended hereto. It willbe apparent to those skilled in the art that modifications can be madein the embodiments chosen for illustration without departing from thespirit and scope of the gesture sensing device.

1. A device comprising: a plurality of light sensors configured todetect light and to output signals in response thereto; and lightmodifying wall structure disposed adjacent to the plurality of lightsensors, the light modifying wall structure configured to selectivelyblock a portion of the light reflected from the object depending on aposition of the object relative to the light sensor assembly, the lightmodifying wall structure comprising a plurality of layers and aplurality of vias, respective ones of the plurality of layers and theplurality of vias offset in a stair-step fashion with respect to acenter axis defined perpendicular to a surface of the light sensorassembly. 2-17. (canceled)
 19. The device as recited in claim 1, furthercomprising an illumination source configured to emit light.
 20. Thedevice as recited in claim 19, wherein the illumination source comprisesa single illumination source.
 21. The device as recited in claim 20,wherein the illumination source comprises a light emitting diode. 22.The device as recited in claim 21, wherein the light emitting diodecomprises a single light emitting diode
 23. The device as recited inclaim 1, wherein respective light sensor of the light sensor assemblycomprises a photodiode.
 24. The device as recited in claim 1, whereinthe plurality of light sensors comprise an array of individual lightsensors.
 25. The device as recited in claim 1, wherein the plurality oflight sensors comprises a single light sensor partitioned into multiplesegments.
 26. The device as recited in claim 1, further comprising aprocessing circuit coupled to the plurality of light sensors to analyzetime dependent signals received from the plurality of light sensors andto determine target object directional movement proximate to the device.27. A device comprising: a light sensor assembly configured to detectthe light reflected from an object and to output signals in responsethereto; and a light modifying wall structure disposed generallyadjacent to a surface of the light sensor assembly, the light modifyingwall structure configured to selectively block a portion of the lightreflected from the object depending on a position of the object relativeto the light sensor assembly, the light modifying wall structurecomprising a plurality of layers extending generally upwardly withrespect to a surface of the light sensor assembly, respective ones ofthe plurality of layers horizontally offset with respect to anunderlying layer in a direction extending from a vertical axis definedwith respect to the surface.
 28. The device as recited in claim 27,further comprising an illumination source configured to emit light. 29.The device as recited in claim 28, wherein the illumination sourcecomprises a single illumination source.
 30. The device as recited inclaim 28, wherein the illumination source comprises a light emittingdiode.
 31. The device as recited in claim 30, wherein the light emittingdiode comprises a single light emitting diode
 32. The device as recitedin claim 27, wherein respective light sensor of the light sensorassembly comprises a photodiode.
 33. The device as recited in claim 27,wherein the plurality of light sensors comprise an array of individuallight sensors.
 34. The device as recited in claim 27, wherein theplurality of light sensors comprises a single light sensor partitionedinto multiple segments.
 35. The device as recited in claim 27, furthercomprising a processing circuit coupled to the plurality of lightsensors to analyze time dependent signals received from the plurality oflight sensors and to determine target object directional movementproximate to the device.
 36. A sensing device comprising: a light sensorassembly configured to detect the light and provide a signal in responsethereto; and a light modifying wall structure disposed generallyadjacent to an edge of the light sensor assembly, the light modifyingwall structure configured to selectively block a portion of the lightreflected from the object depending on a position of the object relativeto the light sensor assembly, the light modifying wall structurecomprising a plurality of metal layers and a plurality of through-vias,respective ones of the plurality of metal layers horizontally offsetwith respect to an underlying layer in a direction extending from avertical axis defined with respect to the surface.